The present invention relates to a tire of the type having a radial carcass reinforcement intended, in particular, for medium tonnage vehicles, such as light utility vehicles or so-called 4.times.4 vehicles. More particularly, it concerns the crown reinforcement of such a tire.
The crown reinforcement is generally formed of two plies of substantially inextensible cables which are parallel to each other within a ply and crossed from one ply to the next, forming identical or different angles of between 10.degree. and 45.degree. with the circumferential direction. The cables used are generally metallic and of steel, and such plies are known as "working" plies.
The tire of the type in question is subjected to different conditions of travel; in particular, it is called upon to travel on ground on which there are stones and obstacles of all kinds which may cut it. The tire and, more particularly, its crown reinforcement is then subject to perforations and cuts of cables with possible penetration of water which causes oxidation of the cables and/or a separation between cables of the same ply or between cables of two plies of the reinforcement.
The improvement in the resistance of a crown reinforcement to such injuries is, as is generally known, obtained by the addition, radially on the outside of the said two working plies, of a third ply of elastic metal cables, known as a protective ply. This solution has the major drawback of being expensive while not giving the best performance.